Cam operated clutch

ABSTRACT

The clutch of the present invention is of the type wherein friction rings associated with a drive member are forced into face-to-face engagement with friction-discs splined to a driven member. The engagement of the friction member is effected by a cam and cam follower mechanism.

United States Patent [1 91 9 Culbertson 1 Feb. 12, 1974 1 CAM OPERA-TEDCLUTCH [75] Inventor: George W..Cu1bertson,

' Oconomowoc, Wis.

[73] Assigne'e: FMC Corporation, San Jose, Calif.

[22] Filed: Mar. 14, 1972 [21] Appl. No.: 234,558

[52] US. Cl. 192/93 A, 74/567 [51] Int. Cl. Fl6d 23/12 [58] Field ofSearch 112/93 A, 70.23

[56] References Cited UNITED STATES PATENTS 2,848,086 8/1958 Warsaw 192/93 A 2,091,270 8/1937 Colman 192/93 X 2,574,204 Woody et a1. 192/932,661,826 12/1953 Hendrickson et a1.... 192/93 2,700,444 l/1955 Ahlen192/93 3,386,547 6/1968 Hansen 192/93 X Primary Examiner-Benjamin W.Wyche Attorney, Agerit, 0r FirmF. W, Anderson; C. E.

Tripp [57] ABSTRACT The clutch of the present invention is of the typewherein friction rings associated with a drive member are forced intoface-to-face engagement with frictiondiscs splined to a driven member.The engagement of the friction member is effected by a cam and camfollower mechanism.

2 Claims, 5 Drawing Figures 1 CAM OPERATED CLUTCH riphery of theplurality of spaced clutch rings 25 (FIG. 1) that are disposed insidethe circle defined by the fingers 17a and have friction materialcemented to their side faces. A clutch disc 27 is positioned betweeneach invention is concerned have been used extensively in fairly heavymachinery installations, such'as farming machinery, to selectivelyengage or disengage drive members and driven members. Such clutches aredisclosed in U.S. Pat. Nos. 2,661,826, 2,827,994, 3,386,545 and3,127,969. In such clutches, the friction discs are moved intoengagement .by a rotary cam mechanism that is actuated by means of oneor more pull rods. While previous clutches have enjoyed a degree ofsuccess, the clutch of the present invention provides an improved camroller arrangement for transmitting force between a cam and itsfollower, and an improved cam contour for effectively applying thetransmitted force.

It is therefore an object of the present invention to provide animproved mechanism for engaging and disengaging the friction discs of .afriction clutch.

Another object is to provide an improved cam mechanism for a frictionclutch.

SUMMARY OF THE INVENTION The clutch of thepresent invention comprises aplusteeply-inclined section for quickly taking up the space between thefriction members when they are initially moved toward engagement, and afinal section of relatively shallow inclination for smoothly andeffectively forcing the friction members into driving engagement.

DESCRIPTION OF THE DRAWING FIG. 1 is a vertical section takenlongitudinally through the clutch of the present invention.

FIG. 2 is a section taken along line 2-2 of FIG. 1. FIG. 3 is aperspective of the cam ring of the clutch of FIG. 1.

FIG. 4 is an elevation of the cam ring of FIG. 3.

FIG. 5 is a fragmentary schematic view showing a development of aportion of the cam ring of FIG. 3.

The clutch of the present invention is adapted to connect a drivingsprocket 10 (FIG. 1) with a driven sprocket 11 that is rotatably mountedon a stationary jackshaft 12.

The driven sprocket 11 is either keyed to or formed integrally with orwelded to a sleeve 14 which is rotatably mounted on jackshaft 12'bybushings 15.

The driving sprocket 10 is formed on the periphery of acup member 17that is rotatably journaled on the sleeve 14 by means of a bearing unit-18. The cup has a spacer plate 19 welded to its inner face, and has aplurality of drive fingers 17a (FIG. 2) that are arranged in spacedrelation around the periphery thereof and project in a directionparallel to jackshaft 12. The drive fingers 17a engage spaced lugs 25aformed on the pepair of adjacent friction rings 25, and each disc 27 hasa plurality of tangs 27a projecting radially inwardly for drivingengagement with splines 29 on the sleeve. 14. It will be evident that,when the friction rings 25 and the discs 27 are moved toward the right(FIG. 1) and pressed into tight engagement witheach other, a drive willbe established between the drive sprocket 1 0 and the driven sprocket11. During suchmovement of the rings and'the discs, the cup member 17 isprevented from moving to the right by a snap ring 30 on the hearing 18,a spacer ring 31, and a snap ring 32 on sleeve 14.

The rings and discs are moved into engagement with each other by meansof a rotary cam roller carrier 33 that is rotatably journaled on thesleeve 14 by a bearing unit 34 which is free to slide axially on sleeve14. This rotary carrier has three angularly spaced cam followers in theform of rollers 35 (FIG. 2) that ride along the surface of a cam ring 37which is rotatably supported on a bearing unit 38 that is also free toslide axially on sleeve 14 (FIG. 1). As seen in FIGS. 3-5, the cam ringhas three angularly spaced cam tracks 40, and each cam track includes adwell portion a that is in a transverse plane generally normal to theaxis of the shaft 12, a relatively steep inclined portion 40b, and arelatively shallow inclined portion 400. When the cam rollers, whichmove in a plane transverse to' shaft 12, are on the dwell portions 40a,the clutch is disengaged and the friction rings 25 and discs 27 are heldout of engagement with each other by Belleville or wave type springwashers (FIG. 1) disposed between the adjacent discs 27 and between anend disc 27 and a pressure plate 46 that is splined on sleeve 14. Itwill be noted in FIG. 1, that movement of the cam ring 37 in an axialdirection toward the left is prevented by a snap ring 47 that is engagedinthe outer race of bearing 38. The bearing 38 is, in turn, held againstaxial movement by a nut 49 that is threaded on the end of sleeve 14.When the nut is screwed onto the sleeve 14 to the position thatdetermines the desired axial position of the cam ring 37, the nut islocked against rotation relative to the sleeve 14 by a key 50 which fitsinto aligned recesses in the nut and in the sleeve. A screw 51 securesthe key to the nut 49.

When the rollers 35 move up the inclined camming surfaces 40b, therotary cam roller carrier 33 is moved towardthe right against a snapring 52, causing the bearing unit 34 to move to the right and press aspacer washer 53 against the pressure plate 46, urging the plate againstthe adjacent friction ring 25. Further movement of the rollers along thecamming surfaces 40b and along the inclined surface 400 moves thefriction rings 25 into driving engagement with the discs 27.

Relative movement between the rotary carrier 33 and the cam ring 37 isaccomplished by rotating the carrier 33 clockwise (FIG. 2) while thering 37 is rotated counterclockwise (FIG. 3). Rotation of carrier 33 iseffected by a longitudinal pull on a rod that is connected through aball joint 61 to an arm 33a formed on or secured to the carrier 33.Slmilarly,'the cam ring 37 is rotated by pulling on a rod 63 (FIG. 3)that is connected through a ball joint 64 (FIG. 1) to an arm 37a rigidlysecured to the ring. The rods 60 and 63 may be actuated by means ofhydraulic power cylinders (not shown).

At least one of the rods 60 and 63 may include an ad justable section,such as a turn buckle, whereby the angular position of the rollers ofthe rotary cam 33 can be adjusted relative to the angular position ofthe annular cam tracks 40 so that, when the rods are in their relaxed orunactuated position, the cam rollers 35 are on the left hand end of thedwell portions 40a of the camming surface, as shown in FIG. 5. Also, itwill be evident that the nut 49 determines the position of the pressureplate 46 when the cam rollers 35 are at the outer end of the camsurfaces 40c as illustrated in phantom lines in FIG. 5. Therefore, byrotating the nut 49, the amount of pressure applied against the frictiondiscs 25 and the discs27 can be adjusted to the desired amount.

A particular feature of the clutch is the configuration of the cam ring37. For a given pull on the rods 60 and 63, the resulting axial clampingforce is determined by the angle of helical inclination of the camtracks 40c on cam ring 40, i.e., the smaller the slope of the cam track,the greater the wedging action and hence the greater the clamping force.

It is readily observed that for a specific degree of angular rotation ofcam ring 40, the resulting axial displacement of the cam roller carrier33 consists of two parts, first the amount necessary to take up theaxial clearances between the friction rings 25 and discs 27, andsecondly the amount necessary to apply the required axial pressure afterthe discs have made a driving engagement or contact.

The first requires little axial force and consequently it can beaccomplished by means of a steep sloped cam surface which offers a lowmechanical advantage. The second requires a considerable axial force andtherefore relies upon a smaller sloped cam surface having a much greatermechanical advantage. The combination of these two slope's can thusproduce more axial force for the same angular displacement of the camring 40 with the same pull on the rods 60 and 63-than could be providedby a camming surface of uniform slope.

A beneficial side effect of this dual slope cam surface is that itallows a deeper dwell portion 40a to provide more clearance betweenfriction rings 25 and discs 27 thereby reducing parasitic drag andallowing a greater volume of cooling media to pass through. the discpack when the clutch is in a disengaged condition.

In one successful arrangement in which the cam track had a mean radius R(FIG. 4) of approximately 2.109 inches, each cam section 40a was in aplane transverse to the jackshaft l2 and had an angular extent ofapproximately 45. Each cam section 40b was inclined 7' from thetransverse plane and had an angular extent of 8; and each cam section400 was inclined 3 from said transverse plane and had an angular extentof 37.

In the disclosed embodiment, both the roller carrier 33 and the cam ring40 are rotatable. It is within the scope of the present invention toposition either the carrier or the ring in fixed position and move theother member relative to the stationary member through the necessaryangular distance. In some arrangements the use of a rod similar to rods60, 63, which move with a generally straight line movement, may besufficient; in others an actuator having some angular movement aroundthe axis of jackshaft '12 will be necessary.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the present invention.

What is claimed is:

1. In a clutch of the type wherein firstclutch members, which areconnected to a driver, are disposed alongside second clutch members thatare connected to a driven member, and are normally held out ofengagement by a separating means but are arranged for movement intoengagement with said second clutch members to establish a connectionbetween said driver and said driven member, the improvement whichcomprises a cam mechanism operatively connected to said clutch membersto move them into engagement comprising a cam ring having a plurality ofcam tr'acks recessed into an axial face thereof, a carrier, followers onsaid carrier, each follower being associated with one of said camtracks, means mounting said cam ring and said carrier for relativerotary movement about a fixed axis to move said followers along said camtracks, each cam track having an elongated idler section in a planesubstantially perpendicular to said fixed axis and terminating at oneend in a stop portion cu'rved steeply away from said plane, a transitionsection of abbreviated length inclined to said plane and disposedadjacent the other end of said idler section, an elongatedpressureapplying section adjacent said transition section that is ofless inclination relative to said plane than is said transition section,said pressure-applying section of each cam track being disposed at anangle of approximately 3 to said plane and terminating in a stop portioncurved steeply away from said plane toward said follower, the 3inclination of the camming surfaces being effective to cause rollersmoving up said surfaces to transmit a desired axial force to said clutchmembers without restricting self-releasing movement of the rollersdownward along said surfaces; and means for effecting relative movementbetween said cam ring and said carrier to move said followers along saidtracks.

2. A clutch according to claim 1 wherein the transition section of eachcam track is disposed at an angle of approximately 10 7 to saidtransverse plane.

1. In a clutch of the type wherein first clutch members, which areconnected to a driver, are disposed alongside second clutch members thatare connected to a driven member, and are normally held out ofengagement by a separating means but are arranged for movement intoengagement with said second clutch members to establish a connectionbetween said driver and said driven member, the improvement whichcomprises a cam mechanism operatively connected to said clutch membersto move them into engagement comprising a cam ring having a plurality ofcam tracks recessed into an axial face thereof, a carrier, followers onsaid carrier, each follower being associated with one of said camtracks, means mounting said cam ring and said carrier for relativerotary movement about a fixed axis to move said followers along said camtracks, each cam track having an elongated idler section in a planesubstantially perpendicular to said fixed axis and terminating at oneend in a stop portion curved steeply away from said plane, a transitionsection of abbreviated length inclined to said plane and disposedadjacent the other end of said idler section, an elongatedpressureapplying section adjacent said transition section that is ofless inclination relative to said plane than is said transition section,said pressure-applying section of each cam track being disposed at anangle of approximately 3* to said plane and terminating in a stopportion curved steeply away from said plane toward said follower, the 3*inclination of the camming surfaces being effective to cause rollersmoving up said surfaces to transmit a desired axial force to said clutchmembers without restricting self-releasing movement of the rollersdownward along said surfaces; and means for effecting relative movementbetween said cam ring and said carrier to move said followers along saidtracks.
 2. A clutch according to claim 1 wherein the transition sectionof each cam track is disposed at an angle of approximately 10* 7'' tosaid transverse plane.